Filament can be dyed during printing by passing it through a permanent marker. This article outlines the colours you get from dyeing opaque white filament with different Sharpie colours.

In 2014, Mathew Beebe published something he called the Ultimate Filament Colorer on Thingiverse. It’s a technique of colouring plastic filament by passing it through the ink sponge inside a Sharpie marker before it feeds into the hotend of a 3D printer. The pigment mixes with the plastic inside the hotend, producing a permanent colour that doesn’t rub off.

When ‘clear’ plastic is coloured, the result is generally the same colour as the Sharpie was. However, no one has documented the colours that result when opaque white plastic is coloured. The answer is that it creates pastel colours (Fig. 1)! In this article, I tested all the Sharpies I could find and documented their final printed colour.

Figure 1. Soma Cube pieces printed with Sharpie-coloured filament. Don’t they look like delicious candy? The Sharpie colours used for these prints are the ones listed in my recommended palette later in this article (plus the uncoloured white filament).

Why colour filament?

It’s a good question. Why make your own coloured filament when you can just buy the stuff?

In short, there are three reasons:

Space. You need to store all that filament somewhere and keep it cool and dry.

Waste. You end up with lots of open spools that need to be used up.

Consistency.

That last point is the big one for me. Filaments from different manufacturers have different temperature profiles. Within a manufacturer’s line, every colour also has its own temperature profile — it might want a hotter first-layer temperature, for example, or it might start stringing at a lower temperature. And due to variations in the manufacturing process, each spool will have a slightly different average filament diameter. You would normally tweak your settings and find a compromise for all of the filaments you want to use, but if you use a single type of white filament and colour it on demand, you don’t have to.

The documentation process

I designed a Sharpie holder for this job (Fig. 2). Its most important function is to hold the Sharpie vertically above my printer’s extruder so that the filament has a straight line through the Sharpie and into the hotend, reducing friction and dragging. By printing each Sharpie’s holder using filament coloured by that same Sharpie, I can also use these prints as a colour reference in the future.

Figure 2. A set of Sharpies in the holders they helped create. The caps are covering the holes drilled into the bottom of the markers, while the holes at the bottom of the holders are sealed with tape.

Sharpies, annoyingly, are not labelled with their colour or even a colour code. I have therefore used Cheryl Shireman’s Sharpie colour reference diagrams to find both the name of the colour and the colour of its cap — Cheryl’s photos are somehow a truer reproduction of the cap colours than the photos on Sharpie’s own website.

I tried to photograph the final prints but I found it really difficult to represent their colours accurately. Instead, I did my best to mix the colour in GIMP’s colour picker while holding the finished print against my screen and under a strong white light. This was much more dependable.

Which makes it a nice base for this research. I printed it at 200 °C on alcohol-cleaned blue tape.

The results

GORGEOUS PASTELS OH MY GOSH

I have been wanting to print in pastels since forever, so this is great!

Standard

Cap colour

Printed colour

Sky Blue

#e8fffc

Turquoise

#bbffdd

Lime Green

#bafcc2

Green

#71e8dd

Pink

#ffe6cd

Magenta

#ffd3ce

Berry

#fbc6d2

Purple

#ffc8fa

Black

#e8e8e8

Orange

#fffca2

Red

#fa8d54

Electro Pop

Cap colour

Printed colour

Ultra Violet

#fffdbd

Nano Blue

#94ffe4

Optic Orange

#ffd2b8

Techno Blue

#9aeaf1

Electric Pink

#f3ecf3

Floral Colours

Cap colour

Printed colour

Pink

Off-white

Sky Blue

Off-white

Peach

Off-white

Lilac

Off-white

Mint

Off-white

Boysenberry

Off-white

Neon

Cap colour

Printed colour

Neon Blue

#aff7f6(Fluorescent)

Neon Pink

#ffe5f2

Neon Yellow

#f3ff9e

Neon Orange

#ffefc4

Metallic

Cap colour

Printed colour

Gold Metallic

#c4d8db

Silver Metallic

#dff7fa

Discussion

Pastels, yes! It sure saves me from importing some of Faberdashery’s great pastel filaments.

Limited colour range

You’ve probably noticed a few oddities, like how some Sharpies produce very similar colours (Turquoise/Lime Green, and Pink/Magenta/Berry). I was also very surprised that none of the Sharpies produced a clean primary colour. Even Red Sharpie created an orange print when I expected it to just dilute and turn pink. I suppose these colour changes come down to the formulation, so markers from other manufacturers should have different formulations and produce their own particular colours.

Also note that all of the Floral Colours markers (the ones that came as pastels to begin with) produced so little colour in the final print that I could barely differentiate them from each other. It seems that the stronger the colour of the Sharpie, the better the printed result.

Desi’s recommended palette

Because so many of the Sharpies produce nearly-identical printed colours, we can omit most of them and just buy a few specific ones to form a pastel palette. Here are the ones I’ve settled with.

The palette of Sharpie colours that I use for printing. The palette is grouped into major colours (yellow, orange, blue, green, purple, and pink). Where possible, each major colour has a darker and lighter shade for subtle two-tone printing.

Cap colour

Printed colour

Orange

#fffca2

Neon Orange

#ffefc4

Red

#fa8d54

Techno Blue

#9aeaf1

Lime Green

#bafcc2

Purple

#ffc8fa

Berry

#fbc6d2

Magenta

#ffcdc7

Pink

#ffe6cd

Neon Sharpie fluorescence

The Neon Sharpies came out with some great colours, but only the Neon Blue print remained strongly fluorescent under UV light (see image below).

Failure of Metallic Sharpies

The Metallic Sharpies failed to produce the expected metallic look under normal operation. It seemed like the metal particles were resistant to being extruded from my 0.4 mm nozzle. The metallic colour could be forced to come out by loading the printer with heavily-coloured filament (the filament was pulled through the Sharpie by hand to leave a thick coating on it), but the printed result was patchy and unreliable, and the nozzle became loaded with metallic particles that took nearly 7 cold-pulls to clean out (although the nozzle never jammed).

Inconsistent colouring from Metallic Sharpie. Printing with heavily-coloured filament did mean that some metallic particles made it into the print, but the result was not attractive.

Debris left in the nozzle from Metallic Sharpie. This is what remained after cold-pulling 5 times. The nozzle never jammed, though.

Considerations

Finally, do note that these results are for 1.75 mm filament. 1.75 mm filament has more than twice the surface area of 3 mm filament per unit area. This means that when the outside of the filament gets coated in ink, there is less plastic inside to dilute the colour. If you wanted to do this with 3 mm filament you would need to piggyback at least two Sharpies, one after the other, to get the same intensity of colour. Note that you cannot mix colours or intensify a single colour by feeding filament into more than one Sharpie. The solvents in the last Sharpie will always scrub the old colour off completely.